The default style of the Gnus summary buffers has been bugging me, so I've changed it to something more palatable. 

(setq gnus-user-date-format-alist
      '(((gnus-seconds-today)           . "Today")
        ((+ 86400 (gnus-seconds-today)) . "Yesterday")
        (604800                         . "%A")
        ((gnus-seconds-month)           . "%A %d")
        ((gnus-seconds-year)            . "%B %d")
        (t                              . "%Y-%m-%d")))

;; U: Unread indicator
;; R: Mark
;; z: Indicates +/- for above/below default score
;; f: Sender
;; B: Tree display
;; s: Subject if root of thread or different from root
(setq gnus-summary-line-format "%U%R%z  %-17,17&user-date;  %-40,40f %B%s\n")